Relay and circuits therefor



March 13, 1928. 1,662,060

J. HERMAN RELAY AND CIRCTS THEREFOR Filed Dec. 3l. 1925 ly 4 INVENTOR A TTORNEY Patented Mar. 13, 1928.

UNITED STATES PATENT- OFFICE.l

JOSEPH HERMAN, OF NEW YORK, N. Y., ASSIGNOR TO AMERICAN TELEPHONE A ND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

RELAY AND CIRCUITS THEREFOR.

Application filed December 31, 1925. Serial No. 78,657.

This invention relates to relays, and more particularly to circuit arrangements for decreasing the operating time ot polar relays.

Cases frequently arise in which a polar relay located at one point and controlling a piece ot apparatus at that point must be operated over a circuit trom a distant point.

For example, where a telephone line is connected to a radio transmitter, an echo supio pressor may be associated with the line at a pointl distant trom the radio transmitter. 1f the echo suppressor is to control the operative condition of the distant radio transmitter, it is highly desirable that the local I5 polar relay at the transmitter station shall be able to pull up and release its armature as soon as possible after the echo suppressor relay has opened and closed the circuit at the distant point. The present invention has 2o for one of its objects to provide a polar relay circuit in which a minimum time lag will occur both in attracting and releasing itsv armature in response to a distant vcontrol operation.

The invention may now be more fully understood 'from the following description when read in connection with the accompanying drawing, Figure 1 of which is a circuit diagram illustrating the type of polar relay circuit heretofore employed; Fig. 2 is aseries of curves illustrating the operation ot' the relay of Fig. 1; Fig. 3 is a circuit arrangement embodying the principles of the present invention; and Fig. 4 is a series of curves showing the operation of the circuit of Fig. 3.

Referring to Fig. 1, a polar relay is shown comprising sets ot windings 6, 7 and 8. The sets o'f windings 6 and 7 are connecte-d in parallel across an operating circuit and comprises the operating winding ot the relay. The set of windings 8 constitutes the biasing windings and are connected in series with the battery through an adjustable resistance 9 by means of which the value of the biasing current may be controlled. The biasing winding is so arranged, either by having its windings reversed with respect to the operating windings or by having the. direction of the current reversed With respect to the operating current, that it produces a pull on the armature 14 of the relay in a direction opposite to that produced by the operating Winding. At some distant point, a controlling relay R may be arranged, the controlling relay having an armature 2. A line conventionally indicated at 5 is connected between the polar relay PR and the controlling relay RA At the point where relay R is located, the potential ot the battery is applied to` the line terminals through a resistance 4, and when the varmature ofl the relay R rests upon its back contact 3, the terminals of this battery supply circuit are short-circuited.

When the circuit is in the condition illustrated with the terminals of the resistance 4 and battery short-circuited, no current flows through the operating windings of the polar relay PR. The current iiowing through the biasing winding 8 holds the armature 14 of the polar relay against its contact 15. V'Vhen the armature of the relay 2 is moved in a direction away from the back Contact 3, the short-circuit ot the terminals of the resistance et and operating battery is opened, and current flows over the line 5 through the operating windings of the polar relay. The operating current produces a pull of greater magnitude and in a direction opposite that ot the biasing winding so that the armature let is shifted away from its contact 15 to the back contact 13. Then the relay R again releases its armature so that the short-circuit is once more closed, the operating current ceases, and the biasing current Yflowing through the biasing winding restores the armature 14 to its contact 15.

Now, when the armature 2 is withdrawn trom ythe back contact 3, it takes an appreciable interval for the polar relay PR to shift its armature 1er` away from the contact 15. This is called the break time of the relay and arises principally through the fact that the line 5 is, in effect, a Series of resistances with shunted capa-cities, which capacities are gradually charged up when the current begins to -How over the line so that the operating windings of the polar relay PR do not receive their full current lat once. It' thebiasing current through the break intervals occur, attention is called to the curves ot Fig. 2. ln this ligure time is plotted as abscissae and the current values as ordinates. Suppose a steady current ot a Vvalue am is flowing; through the biasinl nv'inding` as indicated by the curve l, and that no current is flowing in the operating `winding. lt, at an ii'istant olf time a, the armature 2 leaves the contact 3 so that cui'- rent 'lions into the line, it will take an appreciable time tor the current flowing through the operating windings oi' the relay PR to build up to its tull value, because the capacity ot the line must graduallyy be cbargedto its lull extent bel'ore the current through the relay windings reaches a steady state yalue, as indicated at the top ot' the curve A. Non', since the biasing;` current indicated by the curve B produces a pull in a direction opposite to that produced by the operatine` current, the operating current represented by the curve A must be built up at least to the. value ot' the biasingl current before the armature la can be shifted from its contact, so that it takes at least an interval ot time u?) for the relay PR to shift its armature away from the contact 15 after the armature 2 opens the short-circuit. lf the biasing current was' much larger, so that ithad a value, tor example, ay, the operating current would have to build up to at least this same value, Which would require a time ot at least Lc as the break time ot the relay PR. lt is therefore evident that, to make the break time short, it is necessary to keep the biasing current low in value.

lt, non', We suppose that alter the operating current through the operating windings ot the polar relay lull has reachedits steady state value, the armature is again brought into contact with the back contact 3 atan instant ot time d, the operating current represented by the curve [i `gradually decays owing;W to the capacity ofthe line and does not immediately tall to vaero. lit a small biasing' current, as represented by ll, is used, the operating current niustdrop to a Value lewe;l than fr betere the biasing eurent can become effective to restore the rmature 14 to the contact 15, so that it vidi take an interval ot time at least equal to @if to ctfect. the make operation. lit, of course, the biasing current had a value ay, as shown by the curve C, the make time would only be (Ze. This, as already pointed out, would result in an increase in the break time,Which would be undesirable.

It will beclear from the above discussion that, in order to eecta yquick break time, the biasing current should be ot small value, and, to eliect a quick. make time, the biasing current should` be ot large'value. Ylhe circuit arrangement shown in Fig. 3 is designed to. accomplish this result. As will be seen, the armature 14. of the polar relay reeaoeo FR is so arranged that when it rests on its back contact 13 it will connect a resistance 11 to ground in parallel with the resistance 10. lllhen, however, the armature lll is on niake contact 15, only theresistance l() is in series with the battery supplying the biasing current. Consequently, the resistance in series with the biasingl winding is ot much Vgreater'when the armature 14e is on its contact 15 than when it is on its back contact 13. lly properly proportioninp,I the resistances 10 and 1 1, the two ell'ectire Values of current may bebrought Within any desired limits. yl`his arrangement results Ain increasingthe. biasing current for the make operation. Since the larger biasing,` current would tall to the [smaller value the instant the armature lett the contact 1S, a condenser 12 is connected as shown, so that it Will become charged when the circuit is opened at contact 13, thereby continuing` the loiv oi current for an appreciable length o'l time so that the biasing` current does not immediately drop to its original value.

The operation of this circuit willbe'clear from the curve shown in- Fig. 4. It at an instant ot' 'time a the armature 2 leaves the contact 3, the operating' current begins to Vbuild from zero up to its steady state value gradually as indicated bythe curve A, this part of the operation being' the sameas in Fig, 1. ll' the biasing current have the Value am, as indicated by curve Il, the biasing' current will remainrat this Value until the operating current builds up to an equal or greater `value, so that it may shift the armature lllfroni the contact 15. This Would require a break time represented siiibstantially by the interval c7). its soon as the armature let reaches thecontact 13, the condenser l2 begins to discharge through the right-hand member ot resistance 11 and the biasing' current begins to gradually build up, as indicated, by the curve ll, to a, final Value represented by eli/ rlh'is linal value is less than the steady stato value ot the open ating,` current, so that-the aru'iature 1l-,Will be held against its back contact 13 by the operating current. l

llt, now, atan instant Z the armature 2 is again brought into cotnact 'with the Contact 35 the operating current begins to decay as shown by the curve A, and as soon as it talls toa value ay, the biasing current becomes greater than the operating current, so that the armature 14 is shifted toits make contact 15. The make operation, therefore, Will only require a time substantially equivalent to the interval de. lf We assume that at the instant e the armature lll leaves the contact 13, the biasing current begins to decay as indicated by the rig'hthand portion of the curve B until it drops to its'steady state value am. This gradual decay of the biasing current is due to the actiony of the condenser 12, and it' this condenser were not provided, the biasing current would drop immediately' at the instant e to the value am with the result that the biasing current would again be less than the operating current, so that the operating current might tend to shift the armature back to the contact 13 thus producing a chattering effect.

It will be apparent that by properly proportioning the resistances 10 and 11 and the condenser 12 with respect to the other circuit elements, both the make time and the break time may be brought within any desired limits, and the make time may be made substantially as short as the break time. In actual practice, it has been t'ound that when the circuit 5 is 19-gauge cable of twenty miles in length and the circuit of Fig. 1 isl employed, it requires substantially .0018 seconds to open the contact 15 and .02 seconds to close it. lith the special type oi biasing circuit illustrated in Fig. 3, however, the break time is about .O02 seconds (which it will be noted is substantially the same as in the case of the circuit of Fig. 1), and the make time is reduced to .O05 seconds. Thus. without increasing the break value, the circuit of Fig. 3 enables the make time to be cut down to one-quarter its original value. The make and break times are nearly independent of each other in the circuit arrangement of Fig. 3 and may be adjusted independently by means of the resistances 1() and 11. It is not possible, however, to obtain as small a make time as break time due to the fact that the time required for the armature 111 to travel from one contact to the other must be added to the make time. This is the reason why, in actual practice, using the circuit of Fig. 3, the break time is .002 seconds as compared with a make time of .005 seconds.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated without departing from the spirit of the invention as defined in the following claims.

That is claimed is:

1. A polar relay comprising an operating winding, a biasing winding, and an armature, and means controlled by said relay whereby when the armature is on one of its contacts the biasing current of small but deinite value will How through the biasing winding to produce a pull on the armature opposite to that of the operating winding, and means whereby when the armature is on the other oi" its contacts the biasing current will be increased.

2. A polar relay comprising an operating winding, a biasing winding. and an armature, a. make contact for said armature, and a break contact for said armature, means to determine that a small but definite amount of current will flow through the biasing winding when said armature rests upon its make Contact, and means to increase the amount of said current when the armature rests upon its break contact.

3. A polar relay comprising an operating winding, a biasing winding, and an arma.- turc, a. make contact and a break Contact for said armature, a resistance in circuit with said biasing winding to determine that a small but definite amount of current will flow therethrough when said armature is on its make contact, and means to shunt said resistance when said armature is on its break contact to thereby increase the flow of current through the biasing winding.

4. A polar relay comprising an operating winding. a biasing winding, and an armature, a make contact and a break contact for said armature, a resistance in circuit with said biasing winding to determine the amount of current owing therethrough when said armature is on its make contact, means to shunt said resistance when said armature is on its break contact to thereby increase the flow of current through the biasing winding, and a condenser so connected as to prevent the biasing current from immediately dropping to its make value when the armature leaves the break contact.

In testimony whereof, I have signed my name to this specification this 30th day of December, 1925.

JOSEPH HERMAN. 

